The formats selected for displaying video data have changed over time along with the supporting technologies for displaying the video in these formats. Many, if not most, currently used displays are interlaced due to type of programming available. Interlaced displays render alternate lines of the video every field. Interlacing alternates between drawing the even-numbered lines and the odd-numbered lines of each frame. However, interlaced displays are giving way to high definition progressive televisions.
Progressive or non-interlaced scanning is a method for displaying, storing or transmitting moving images in which the lines of each frame are drawn in sequence. Modern progressive scan displays do not suffer as much from line flicker or scan line visibility in comparison to interlaced displays. These advantages are more pronounced when the size of the display is large or when the screen is viewed from close proximity. However, despite the greater acceptance and use of progressive displays, much of the video material available for viewing or broadcasting is still in the interlaced standard definition format. To display an interlaced picture on a progressive display, the video may be converted to progressive format through a line-doubler or a de-interlacer. However, many line-doublers used as de-interlacers introduce display artifacts that reduce the quality of the video being displayed.